Addition compounds of surface active sulfuric acid semiester salts and sulfobetainesand the production thereof



United States Patent Germany No Drawing. Filed Apr. 10, 1963, Ser. No. 271,868

Claims priority, application Germany, Apr. 14, 1962,

7 Claims. Cl. 260-401) This invention relates to addition compounds of surface active sulfuric acid semiester salts and sulfobetaines and to a process of preparing them.

If a cation surfaceaactive or capillary-active substance, such as for example trimethyl-dodecyl-ammoniurn chloride is combined in an aqueous solution with an anionic surfaceaactive or capillary-active substance, such as for example dodecyl sodium sulfate or sodium alkylbenzenesulfonate, then there will be formed because of an ion reaction, in addition to the corresponding inorganic salt, such as sodium chloride, in this particular instance, salts which are almost insoluble in water and which combine within themselves the particular organic ions of the two starting materials. These salts, which are almost insoluble in water, have been described in the literature as non-ionizing or electro-neutral salts. The electroneutral salts are formed according to the following illus wherein X and X represent alkyl radicals containing 8-22 carbon atoms. The electro-neutral salts are more or less insoluble in Water in dependence of the chain lengths of the alkyl radicals X and X and in dependence on the extent to which the sum of the carbon atoms in all of the hydrocarbon radicals, and particularly those present in the form of methyl and methylene groups, exceeds a certain value. On combining the aqueous solutions of the two starting reactants, the salts precipitate out and can be easily isolated in this form. The electro-neutral salts which are almost insoluble in water have, as has been noted above, been described in the literature including the patent literature.

The aliphatic sulfobetaines which are set forth in German Auslegeschrift 1,018,421, and which contain alkyl radicals of higher molecular weight attached to the quaternary nitrogen atom, behave differently from the aforementioned cation capillary active substances. The sulfobetaines which are contemplated by the German Auslegeschrift 1,018,421 are ionizable and form a quaternary ammonium cation and a sulfonate anion, yet differ known quaternary ammonium sulfon'ates and quaternary ammonium-alkyl-sulfates insofar as the two ions are intramolecularly bound. Intramolecular quaternary salts, the anionic sulfo group'of which is firmly bound by principal valence to one of the alkyl radicals attached to the nitrogen atom do not form water soluble compounds with anionic surface active compounds, least of all with fatty alcohol sulfates or alkyl and alkylbenzene sulfonates as is the case with the known cationic compound trimethyl dodecyl-arnmonium chloride, a fact which is disclosed in the Auslegeschrift referred to above, without giving any reasons.

It is an object of the invention to provide electroneutral salts which are water soluble by reaction of an aliphatic sulfobetaine with an anionic surface active compound.

ICC

It is a further object of the invention to provide electro-neutral salts which dissolve in water to produce an increase in viscosity, therein.

It is still a further object of the invention to provide a Water-soluble capillary active reaction product of an aliphatic sulfobetaine and an anionic surface active compound having valuable dispersing and emulsifying properties.

Another object of the invention is a method for producing electro-neutral salts which are water soluble by reaction of an aliphatic sulfobetaine with an anionic surface active compound.

Other and further objects of the invention will become apparent from a study of the within specification and accompanying examples.

It has been surprisingly discovered in accordance with the invention that surface-active sulfuric acid semiesters, and their salts react with surface active sulfobetaines where at least one of the reactants is present in the form of its solution in water or other inorganic or organic solvent to form water soluble surface active products providing that the concentration of the sulfuric acid semiester and sulfobetaine in the aqueous or other solution is greater than the concentrations generally employed in the preparation of compounds constituting wetting agents and namely amounts to at least 2 weight percent of the total reaction mixture composed of the reactants .and solvents.

Its assumed that the concentrations of the :alkylsulfate and sulfobetaine solutions the combination of which is described in the German Auslegeschrift 1,018,421, were on the order of those customarily used for preparing wetting agents and/or detergents and which is generally far below 1%. Under these circumstances, it has not been possible in accordance with the prior art to form addition products which dissolve in water and in connection with which there is observed, as is the case in accordance with the invention, when the solutions of the sulfuric acid semiester and sulfobetaine are combined, an increase in viscosity and which becomes readily apparent, for example in the case of C -alkyl compounds at concentrations of from 5% or 7.5% and more.

On the basis of the above findings, the pouring time of the dodecylsulfate solutions, of solutions of a sulfobetaine prepared from dodecyl-dimethylamine and propane-sultone and of mixtures of such solutions were measured at 20 degrees C., using for the measurements a nozzle of 2 mm. diameter in a Ford pouring vessel. The data derived from these tests showed that at concentnations of up to 3% by weight, scarcely any difference could be observed in the pouring times of fatty alcohol sulfate solutions, sulfobetaine solutions or mixtures of the two solutions but that with concentrations of above 3% a clearly apparent increase in the viscosity of the alkyl sulfate-sulfobetaine solution could be observed as the concentration thereof in the solution was increased. When the starting materials, and in particular the sulfobetaines, contained higher fatty acid radicals, as for instance those containing 16 carbon atoms, the increase in viscosity was measurable even at lower concentrations, as for example at concentrations as low as 2 weight percent.

The cause of the viscosity increase may be considered to be the result of the formation of salts as set forth in the following equation in connection with a sodiumfatty alcohol sulfate and a sulfobetaine:

wherein X and sometimes R represent aliphatic hydro- Patented August 30, 1966 carbon radicals containing 8-22 carbon atoms which can be bound to the nitrogen directly or through an intermediate radical containing hetero atoms or hetero atom groups, X is a hydrocarbon radical having 822 carbon atoms R and in some cases R each represent a straight chain or branched chain aliphatic, cycloatliphatic, or arylaliphatic hydrocarbon radical having at most 7 carbon atoms, which can be bonded directly to one another or through an intermediate, and R stands for a 1,3- propylene or 1,4-butylene radical which may be substituted. In the case where R represents a hydrophobic radical, the sum of the carbon atoms contained by X and R should not exceed 22 and preferably should not exceed 18.

This hypothesis finds some confirmation in the fact that the addition compounds, which for the sake of simplicity will be called salts hereinafter, can be isolated in a uniform crystalline form. Other anionic surface active or capillary active substances, and in particular aliphatic or alkylaromatic sulfonates behave differently. It has been found that in the latter instances the equilibrium of the above equation is evidently shifted towards the left to a greater extent and it is impossible to isolate any well-defined and crystallized salts.

The fact that, when equimolar amounts of a sulfo betaine and a fatty alcohol sulfate are combined in an aqueous medium, a reaction corresponding to the above equation takes place and that it does not take place when salts of sulfonic or c-arboxylic acids are used in place of the fatty alcohol sulfate is apparent from a series of observations as follows:

When an aqueous solution containing, in addition to a fatty alcohol sulfate, such as for example sodium dodecyl sulfate, an equimolecular amount of a sulfobetaine such as for example the sulfobetaine prepared from dimethyldodecylamine and 1,3-propanesultone, is evaporated to dryness, a residue is obtained which can be recrystallized from alcohol as often as is desired without any change occurring in the composition corresponding to the reaction product shown on the right hand side of the above equation, which, in view of the ready solubility of the sulfobetaincs in alcohol, ought not to be the case if the two components are present merely as a mixture of reactants corresponding to those shown in the left hand side of the equation. However, if in place of the sodium dodecyl sulfate, the alkali metal salts of an aliphatic or aromatic sulfonic acid are used, such as for instance dodec-anesulfonic acid sodium or 4-decylbenzenesulfonic acid sodium, the very first crystallization product is free of nitrogen.

The same findings are observed when carboxylic acid salts are used, such as for example sodium laurate.

Furthermore, it has been found that the salts obtainable from a particular fatty alcohol sulfate and a particular sulfobetaine depending on the size of their hydrocarbon radicals are more or less readily and clearly soluble in aromatic hydrocarbons such as toluene, which could not be explained if a mixture containing a free sodium-fatty alcohol sulfate were involved, as sodiumfatty alcohol sulfates are practically insoluble in aromatics, even when heated. On the other hand, similar evaporation residues obtained by using the identical sulfobetaine and a comparable sulfonate are not entirely soluble in aromatics.

Still further, the above reaction explains the finding that aqueous solutions of quantities of a fatty alcohol sulfate and of a long-chain substituted sulfobetaine exhibit when combined a striking :and unusually great increase in viscosity when the concentration in the solutions is great enough, and also the finding that difiiculty soluble fatty alcohol sulfates and difiicultly soluble sulfobetaines, such as those containing a hydrocarbon radical of 18 carbon atoms, go clearly into solution just as soon as an equivalent amount of the other salt-forming reactant is added. This phenomenon is especially impressive in the case of those sulfobetaines which are extremely diificult to dissolve in water, as for example those prepared from methyl benzyl dodecylamine and propanesultone, or those prepared from dimethyl dodecylamine or methyl benzyl dodecylamine and propanesultone, the latter being substantially insoluble in water. All of these sulfobetaines can be brought easily into aqueous solutions by the addition of an equivalent amount of sodium dodecylsulfate, and these solutions can then be diluted at will without any resulting separation taking place.

The above experimental data establishes that the reasons for the failure for precipitation to occur when aqueous solutions :of sulfobetaines and inorganic surfactants are combined which was disclosed without explanation in German Auslegeschrift No. 1,018,421, differs according to whether fatty alcohol sulfates or their related sulfatization products are used or whether other anionic substances and in particular salts of surface active sulfonic acids are used in their place. Whereas in the case of the last-named substances no reaction in the sense of the formation of electro-neutral salts appears to take place, and precipitation does not take place for this reason, there is no precipitation in the case of the firstnamed substances because the salts of the electro-neutral type which presumably form according to the reaction formula set out above, dissolve easily in water as a consequence of the neutralized sulfo group that is formed at the terminus of the one nitrogenous alkyl radical, particularly when the salts which are formed contain two bydrophobic hydrocarbon radicals. These electro-neutral salts, which can be readily produced and are easy to isolate by the methods previously described and which have a terminally placed sulfo group and which crystallize easily if pure starting substances are used in their preparation, are novel compounds which as yet have not been described in the literature as to their composition and their characteristics and represent stable compounds which can be stored in solid form as long as desired.

The water-soluble electro-neutral salts in accordance with the invention prepared from sulfobetaines and surface active sulfuric acid semiester salts represent valuable emulsifying and dispersing agents, and particularly so when the sulfobetaine starting materials contribute one or two hydrophobic radicals. The novel addition compounds of the invention can be used for a great many technical applications. Their special characteristics, namely that many of the salts are readily soluble both in organic solvents and in water forming solutions with water of considerably increased viscosity, render the same eminently suitable for use as dispersing and emulsifying agents, for increasing the wetting, foaming, cleansing and washing capacity of detergent preparations, etc. The salts of the invention are highly insensitive to water hardening substances which property makes them particularly desirable for use in connection with the manufacture of detergent preparations. The compounds of the invention are very similar to the fatty alcohol sulfates in their behavior and their relatively simple preparation offers the possibility of converting difiicultly soluble sulfates, such as tallow alcohol sulfate or octadecylsulfate, to a readily usable form. The salts of the invention find particular utility as emulsifiers or dispersing agents for use in polymerization reactions carried out in a heterogeneous system and in their use in the manufacture of products for the cosmetic industry, such as for instance, ointments, emoluents, creams, etc.

The novel products of the invention can also be used as wetting agents or foam stabilizers in fields which have nothing to do with the washing and cleaning of textiles, or any other objects. Such applications include, for example, the manufacture of fire extinguishers or protectivefoams, air-entrained concrete, auxiliary agents for foam plastics, etc.

The sulfobetaines contemplated for use in the preparation of the salts of the invention may be prepared easily and in good yield by reacting tertiary amines having one or more hydrophobic hydrocarbon radicals, i.e., hydrocarbon radicals containing from 8 to 22 carbon atoms with sultones, particularly 1,3-sultones and 1,4-sultones. These sulfobetaines, as they will be referred to hereinafter, correspond to the general formula:

in which X and in some instances, R are hydrophobic hydrocarbon radicals containing 8 to 22 and preferably to 18 carbon atoms which can be bound to the nitrogen directly or through intermediate radicals containing hetero atoms or hetero atom groups, R and in some cases R each represent a straight-chain or branched chain aliphatic, cycloaliphatic, or araliphatic hydrocarbon radical having at most 7 carbon atoms which can be linked directly to one another or through an intermediate, and R stands for 1,3-propylene or 1,4-butylene radicals, which may be substituted. In the case where R represents a hydrophobic radical, the sum of the carbon atoms contained by X and R should not exceed 22, and preferably should not exceed 18.

Among the aliphatic tertiary amines used as starting materials for the sulfobetaines for use according to the invention are those amines which contain attached to the nitrogen atom a maximum of 2, and preferably only one high molecular aliphatic hydrocarbon radical of a hydrophobic nature and at least one but preferably two lowmolecular, aliphatic, cycloaliphatic, or araliphatic hydrocarbon radicals. The high molecular weight hydrophobic straight or branched chain, saturated or unsaturated, aliphatic or cycloaliphatic radicals contain about 8-22 carbon atoms and preferably is an alkyl radical having about ID -l8 carbon atoms which can be connected directly or via an intermediate linking hydrocarbon radical with a nitrogen atom of the molecule. Among the radicals contemplated as within the scope of the invention are the following alkyl radicals: octyl, including di-a-ethylhexyl, nonyl, decyl, undecyl, dodecyl, including 2-butyl-octyl, tert. dodecyl, etc, tridecyl, tetradecyl, including 7-ethyl-2 methyl undecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nondecyl, eicosyl, including the usual fatty radicals such as lauryl, myristyl, cetyl, stearyl, oleyl, other branched chain radicals, the corresponding unsaturated radicals, alkylethers, such as alkoxy including octyloxy, lauryloxy, cetyloxy, etc. alkyloxyalkyl, such as lauryloxyethyl, myristyl oxy ethyl, cetyloxyethyl stearyloxyethyl, oleyloxy-ethyl-, the corresponding -oxy-methyl-, oxy-propyl-, etc. radicals, alkylcyclohexyl, such as ethyl cyclohexyl, etc., alkaryl, such as alkylphenyl, including octylphenyl, lauryl phenyl, cetyl phenyl, diheptabenzyl, xylyl, etc., aryloxyalkyl ether and alkaryloxyalkylet-her, such as phenoxyakoxyalkyl, and alkylphenoxyalkoxy alkyl, including phenoxy, ethoxyethyl, octylphenoxyethoxyethyl, nonylphenoxy-ethoxyethyl, di-tert. octylphenoxy-ethoxy ethyl, the corresponding methoxy-methylmethoxy-ethyL- methoxy-propyl, -ethoxy-methyl, -ethoxypropyl-propoxy-methyl, -propoxy-ethyl-, propoxy-propyl, etc., diisoheptahydroxyethyl, etc. The low molecular weight, aliphatic, cycloaliphatic or araliphatic hydrocarbon radicals contain from 1-7 and preferably 1-3 carbon atoms and may be connected together to form a ring directly or by heterocyclic intermediate members such as a lower alkyl or a cycloalkyl radical. Among the amines so included are, for example the following: N-dimethylamine, N-diet'hylamine, N-methyl-benzyl-dodecyl, tetradecyl, hexadecyl, or octadecylamine, diisopropyl-hexadecylamine, N-methyl-dioctylamine, N-ethyl-didodecylamine, N-dodecyl-piperidine, N-hexadecyl-morpholine, NN-diethylene oxide-dodecylamine, N-ethylene oxide-didodecylamine, NN-dimethyl-N-dodecyl-ethylene oxide-amine, NN-dimethyl-N-ethylene oxide laurate, and

others. Bifunctional tertiary amines can also be used such as, for example NN-dimethyl-NN-didodecylethylenediamine, NN'-didodecyl-piperazine, NN-ethylene oxide piperazine dilaurate, etc. which produce bifunctional sulfobetaines when reacted with 2 mols of a sultone.

The sultones to be given primary consideration for use in the preparation of sulfobetaines in accordance with the invention are preferably those which are already being prepared in connection with other processes, as for instance the unsubstituted alkane sultones and in particular 1,3-propanesultone and 1,4-butanesultone. However, there may be used to equal advantage in the reaction with the abovementioned tertiary amines, the substituted alkane sultones as for example the 1,3-propane and 1,4- butanesultones which derive from pentanes, hexanes, heptanes, etc., i.e., those in which the propylene or butylene radical is substituted by lower alkyl radicals having less than 6 carbon atoms, such as 2-ethyl-1,3-propanesultone, 2-methyl-1,4-butanesultone and others.

The sultones for use in the process of manufacturing the sulfobetaines are readily obtainable by the conventionally practiced prooedures. It is also possible, however, to use those sultones which are produced from terminal olefins of the formula given hereinafter and which have been described in German patent application H 44,357.

The olefins used as starting materials have the general formula R R R C-CH C=CH wherein R R and R represent hydrogen or aliphatic hydrocarbon radical containing, for example 4 to 7 carbon atoms, although higher olefins, having for example 8 to 20 carbon atoms in the molecule can also be used. These olefins are reacted with sulfur trioxi-de and then, either (a) The reaction product obtained is subjected to a vacuum distillation, or

(b) The sulfonation product is converted by hydrolysis to an oxysulfonic acid, and thereafter water is split off from the latter at an elevated temperature in vacuo with or without the use of an entraining agent.

The reaction of the sultones with the tertiary amines can be carried out in the conventional manner with or without the use of an organic solvent. As organic solvents, there can be used an alcohol or acetone. It is also possible to carry out the reaction in Water, and this is particularly advantageous when the substantially more reactive 1,3-sultones are used. This is of considerable importance for practical, large-scale operations if care is taken to see that the temperature does not exceed 50 C. during the reaction so as to avoid the possibility of hydrolytic cleavage taking place.

If sultones having 8 to 20 carbon atoms are used, such as those prepared according to German patent application H 44,357 they will already contain the hydrophobic hydrocarbon radical which is responsible for the surface activity of the sulfobetaines to be made therefrom and which, in the case of the other sultones, is not introduced into the molecule until it is reacted with the tertiary amine. It is, therefore, possible to react these sultones with other tertiary amines, that is, those containing no hydrophobic radicals in order to produce the sulfobetaines. If tertiary amines having hydrophobic radicals are used in the reaction with the sultone having such hydrophobic radicals, sulfobetaines will be obtained which contain at least two hydrophobic radicals in the molecule.

The sulfobetaines to be used according to the invention can also be obtained according to the process described in German patent application H 42,904 by causing qua- Iterna-ry amines containing both an allyl radical and at least one high-molecular alkyl radical to react in an aqueous solution with sulfite and oxygen. In Example '17 of the said patent, a description is given of the preparation of a sulfobetaine containing the radical of a dimethyl- 12C13-Cfatty amine.

The sunface active sulfuric acid semiesters which can be reacted with the above-described sulfobetaines to produce the salts of the invention include practically all of the sulfatation products and their salts which can be produced by the known methods of sulfatization of highmolecular alcohols or high-molecular olefins, providing that the latter contains a sulfatizable, aliphatically bonded hydroxy group or a sulfatizable ethylene double bond and a hydrophobic hydrocarbon radical, i.e. higher alkyl group of, for example 8 to 2 2 and preferably 10 to 18 carbon atoms, which can be straight-chained or branch chained and which may also be of an unsaturated nature. Among the substances contemplated are the alkylsulfonates, the alkylbenzenesulfonates, fatty acid sulfonate salts, esters, etc., fatty alcohol sulfates, and olefin-sulfonates, as well as fat-alcohol-glycerine ether sulfates,

fat-alcohol-polyglycol-ether-sulfates, fatty acid-mono-ondiglyceride sulfates, etc.

The sulfobetaine-sulfuric acid semiester salts of the invention may be prepared by contacting the sulfobetaine and sulfuric acid semiester salts in the presence of an inorganic or organic solvent for dissolving at least one of the components. The reactants employed amount to at least 2 and preferably more than 3% by weight of the mixture of solvent and react-ants, these concentration figures referring to those quantities of components equivalent to one another, which can react with one another and do not allow for any excess of the two components.

Within these general prescriptions the process of the invention is subject to a wide range of modifications and variations. For example, solutions of the components which form the desired salt may be admixed but it [is also possible to combine one of the two components in undissolved form with the other component dissolved in an appropriate solvent. This latter method of salt formation frequently takes place with a decomposition of one of the two components. This is especially striking when at least one of the two components is difficultly soluble in the solvent. Lastly, the components can be mixed with one another as solids in the presence of an appropriate solvent, for at least one of them.

In all of these procedures, the components may be employed in solid, dry, or in the form of aqueous pastes thereof or as more or less concentrated solutions thereof, a particular preferably embodiment, for example, consists in using the surface active sulfuric acid semiesters and their salts in the form in which they are industrially produced. The sulfobetaines, too, can be used in the form in which they are produced, i.e. as industrial crude products by the reaction of a dialkyl-fatty amine and sultone in the presence of an aqueous or organic solvent.

When the components for forming the novel salts of the invention are used in concentrations of more than 5, particularly of more than 7.5 weight percent, it may become necessary, because of the fact that the viscosity of the resulting solutions or pastes increase rapidly as the concentration increases, to mix the components or their solutions or pastes very thoroughly. Appropriate equipment can be used for this purpose, such as kneading mills, rolling mills, extruding machines, kneading pumps, disk mills, and other such apparatus. If appropriate equipment is used, it is possible, depending on the length of the hydrophobic radicals and the solvent used, to operate in concentrations of up to about 50% by weight, and preferably up to about by weight.

Suitable solvents for carrying out the process of the invention are all of the organic and inorganic solvents which dissolve at least one of the two components and, if desired, the salt reaction product as well. These solvents should have a boiling point of between 30 and 200 C. and preferably of between to 150 C., especially if it is subsequently desired to effect a separation of the solvent from the salt.

The most important inorganic solvent is water. Organic solvents especially suitable for the preparation of the novel salts include oxygen-containing organic solvents of the aliphatic, cycloaliphatic, or aromatic alcohol type, or ethers, partial ethers or ketons containing 1 to 8 and preferably 1 to 4 carbon atoms in their molecule, especially if they are themselves water-soluble. They include methyl, ethyl, propyl, and butyl alcohol, acetone, methylethylketone, diacetone alcohol, acetophenone, ethylene or propylene glycol, glycerin, and in some instances etherification products still containing free hydroxyl groups. The polyvalent alcohols can be used in mixtures one with the other and/ or in mixtures with any of the aforementioned univailent alcohols, cyclohexanole or methylcyclohexanol, and benzyl alcohol, and their hydration products. Hydrocarbons having 5 to 18 and preferably 6 to 10 carbon atoms in the molecule are also suitable as solvents for carrying out the process, as for example the straight chained or branched .aliphates, cycloaliphates, including the hydroaromatics and aromatics or alkylaromatics. The following solvents are given as illustrative examples: mixtures of aliphatic and/or cycloaliphatic and/or aromatic hydrocarbons, such as those produced in the industrial production of motor fuels, benzene, toluene, xylenes and their hydration products, etc.

The salts which are formed can be recovered by concentration and isolation, by for example, evaporating off the solvent and crystallizing out of lower aliphatic alcohols, such as methanol, ethanol, isopropanol, etc. The salt formation can be combined with the subsequent crystallization by contacting the components and the alcohol together at elevated temperatures in such quanti-' ties that the salt formed is just barely completely dissolved and crystallizes out upon cooling.

The sulfobetaine-sulfuric acid semiester salts can also be prepared in the presence of substances with which they are to be used subsequently providing that these sub stances, such as for instance high-boiling hydrocarbon oils, fatty oils, fatty alcohols, parafiins, high-molecular esters, etc., in the liquid state, have some ability to dissolve the components. The separation of the salts from the solvent is then unnecessary.

The following examples serve to illustrate the invention but they are not intended to limit it thereto. In the examples formulae are given which are intended to show the apparent constitution of the salt-like addition compounds produced in accordance with the invention, but no guarantee can be given of the absolute correctness of these formulae.

(a) A 10% aqueous solution of 28.8 parts by weight of sodium dodecylsulfate (0.1 mole), are added to a solution of about 10% of 33.5 parts by weight of the sulfobetaine obtained from dimethyl-dodecylamine and 1,3-propanesultone (0.1 mol). The clear and viscous solution thus produced [is adjusted to a pH of 7 to 8 by the addition of a few drops of dilute caustic soda solution in order to protect the sulfate contained therein, and the solution is then evaporated to dryness, preferably at reduced pressure, or it can be converted into a powder in the conventional manner by atomization carried out while the solution is still hot. The salt thus produced, consisting of equimolar amounts of both components is obtained by recrystallization in the form of uniform flakes from 5 to 8 times the amount of alcohol, and even after repeated recrystallizations has the com position corresponding to the above formula. If an excess of sulfobetaine is used in producing the salt, the same salt is obtained in the crystallization.

(b) The same crystallized salt as obtained in (a) is produced by dissolving equimolar amounts of the two starting materials in 8 times the amount of alcohol at an elevated temperature, and permitting the salt to crystallize.

9 The salt obtained by either method (a) or (b) as a solid crude product or in crystallized form is readily soluble in water and produces solutions of high viscosity having excellent foaming capacities. The salt is flurthermore soluble in heated benzene. The salt can be used as an emulsifier cfor polymerization reactions.

Example 2 Uniformly crystallized salts of similar composition are obtained according to the process of Example 1 by using, in place of sodium dodecylsulfate, an equivalent amount of sodium ootadecyls-u-lfate, and/or a molar amount of the sulfobetaine which is obtained from dime-thyl-octadecylamine and 1,3-propanesultonel I' hese fatty alcohol sulfate-sulfobetaine salts are readily soluble in water, even where they contain two octadecyl radicals in the molecule. They produce highly viscous aqueous solutions and can lbe used for the manufacture of stable emulsions in connection with the cosmetic industry.

Aqueous solutions containing by weight of equimolar amounts of sodium dodecyl-oxethylsulfate and sulfobetaine which is obtained from dimethyltetradecylamine and 1,3-propanesultone are combined and the mixture is converted into a powder by atomization of the salt at 100 C. The salt which is obtained in pure form from the resulting technical product by recrystallization [from 7 times the amount of isopropanol corresponds to the above composition, even after repeated recrystallizations.

Example 4 In the same manner as described in Example 3, a salt is obtained having the above formula by combining solutions of about of eqruimoiar amounts of the sodium salt of lauric acid monoethanolamidesul furic acid semiester and the :sulfobetaine prepared from dimethyl-dodecylamine and 1,3-propanesultone. After removal of the solvent, the salt can be recovered in uniformly crystalline and analytically pure form by recrystallization from 10 times the amount of isopropanol, or, if the reaction was performed in isopropanol, directly from the reaction mixture.

Example 5 A mixture of 250 parts by weight of dimethyltetradecylamine (1 mol) and 500 parts by Weight of water, is added gradually with agitation to a total of 122 parts by weight of 1,3-propanesultone (1 mol), the mixture being cooled occasionally to prevent the temperature from exceeding 50 C. 4000 parts by weight of water are added, followed by 5000 parts by Weight of an aqueous solution containing 288 parts by weight of sodium dodecylsulfate '(1 mol) to the resulting sulfobetaine solution, which has become clear after 6 hours of stirring. The viscous mixture, which is formed is adjusted to a pH of 7-8 and sprayed in a Krause tower at 100 C. 590 to 610 parts by weight of a light dry powder are obtained from which the salt can be recovered in pure crystalline form, if desired, by recrystallization out of alcohol.

Example 6 In the same manner as described in Example 5, a similar salt is obtained proceeding from a technical dimethylalkylamine mixture the alkyl radicals of which contain 12 to 18 carbon atoms, and a molar amount of a sodiumalkylsulfate mixture having alkyl radicals which also conamount of ethanol.

10 tain 12 to 18 carbon atoms. The powder obtained by spray drying is dry, odorless and readily soluble in water.

CH3 CH2CH:4CH2 CH2SOaNa To a 10% aqueous solution of sodium-dodecylsulfate, an equally concentrated solution is added of the sulfobetaine obtained by reaction of dimethyl-dodecylamine with 1,4-butanesultone. The residue remaining after evaporation of the water can be obtained in the form of uniform crystals by recrystallization from 4 times the These crystals have a composition corresponding to the above formula, even after further recrystallization.

The German patent applications, mentioned in the above text correspond to the following US. patent applications:

German Auslegeschrift 1,018,421=U.S. patent application Ser. No. 313,054 German application H44,357:U.S. patent application Ser. No. 242,361, and now U.S. Patent No. 3,164,608 German application H42,904= U.-S. patent application Ser. No. 200,046, and now abandoned The structural formulas of the addition compounds occurring throughout the description, the examples and the claims may have a certain probability of correctness. Nevertheless they are to be considered more as an expression of an hypothetical idea than as the result of an exact analysis of structure.

I claim:

1. A compound of the formula 2. A compound of the formula 5. The process of preparing surface-active compounds, which comprises reacting a surface-active sulfuric ac1d semi-ester with a surface-active sulfo-betaine having the formula:

wherein X is alkyl of 8 to 22 carbon atoms, R and R are each alkyl of 1 to 22 carbon atoms, and -R is a member selected from the group consisting of propylene and butylene, wherein R and X together contain not more than 22 carbon atoms in a liquid medium constituting an inert solvent selected from the group consisting of alcohols, ketones, ethers, and hydrocarbons, said reactants being present in an amount of 2 weight percent of the mixture of the reaction components and said liquid medium.

6. Process according to claim 5, wherein said solvent is a member selected from the group of liquid solvents having a boiling point of 30 to 200 C.

7. The process of preparing surface-active compounds 1 1 which comprises reacting a surface-active sulfuric acid semi-ester with a surface-active sulfo-betaine having the formula:

X2 wherein X and R are each alkyl of up to 7 carbon atoms, R is a member selected from the group consisting of propylene and butylene, R and R are each alkyl of 8 to 22 carbon atoms, wherein R and R together contain not more than 22 carbon atoms in a liquid medium constituting an inert solvent selected from the group consisting of water, alcohols, ethers, ketones, and hydrocarbons, said reactants being present in an amount of at least 2 weight percent of the mixture of the reaction components and said liquid medium.

References Cited by the Examiner UNITED STATES PATENTS 1,944,300 '1/ 1934 Ott et a1. 260513 1,999,432 4/1935 Ulrich et a1. 260-513 2,139,276 12/1938 Lehner et a1 260457 X 2,459,062 1/ 1949 Cook et a1 260-4045 FOREIGN PATENTS 866,787 2/ 1953 Germany. 589,948 12/1933 Germany.

CHARLES B. PARKER, Primary Examiner.

F. D. HIGEL, Assistant Examiner. 

1. A COMPOUND OF THE FORMULA
 3. A COMPOUND OF THE FORMULA
 5. THE PROCESS OF PREPARING SURFACE-ACTIVE COMPOUNDS, WHICH COMPRISES REACTING A SURFACE-ACTIVE SULFURIC ACID SEMI-ESTER WITH A SURFACE-ACTIVE SULFO-BETAINE HAVING THE FORMULA: 